ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 203 insertions, 0 deletions

diff --git a/drivers/leds/leds-regulator.c b/drivers/leds/leds-regulator.c
new file mode 100644
index 000000000..5ba0f36b2
--- /dev/null
+++ b/drivers/leds/leds-regulator.c
@@ -0,0 +1,203 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * leds-regulator.c - LED class driver for regulator driven LEDs.
+ *
+ * Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it>
+ *
+ * Inspired by leds-wm8350 driver.
+ */
+
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/leds.h>
+#include <linux/leds-regulator.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+
+#define to_regulator_led(led_cdev) \
+	container_of(led_cdev, struct regulator_led, cdev)
+
+struct regulator_led {
+	struct led_classdev cdev;
+	int enabled;
+	struct mutex mutex;
+
+	struct regulator *vcc;
+};
+
+static inline int led_regulator_get_max_brightness(struct regulator *supply)
+{
+	int ret;
+	int voltage = regulator_list_voltage(supply, 0);
+
+	if (voltage <= 0)
+		return 1;
+
+	/* even if regulator can't change voltages,
+	 * we still assume it can change status
+	 * and the LED can be turned on and off.
+	 */
+	ret = regulator_set_voltage(supply, voltage, voltage);
+	if (ret < 0)
+		return 1;
+
+	return regulator_count_voltages(supply);
+}
+
+static int led_regulator_get_voltage(struct regulator *supply,
+		enum led_brightness brightness)
+{
+	if (brightness == 0)
+		return -EINVAL;
+
+	return regulator_list_voltage(supply, brightness - 1);
+}
+
+
+static void regulator_led_enable(struct regulator_led *led)
+{
+	int ret;
+
+	if (led->enabled)
+		return;
+
+	ret = regulator_enable(led->vcc);
+	if (ret != 0) {
+		dev_err(led->cdev.dev, "Failed to enable vcc: %d\n", ret);
+		return;
+	}
+
+	led->enabled = 1;
+}
+
+static void regulator_led_disable(struct regulator_led *led)
+{
+	int ret;
+
+	if (!led->enabled)
+		return;
+
+	ret = regulator_disable(led->vcc);
+	if (ret != 0) {
+		dev_err(led->cdev.dev, "Failed to disable vcc: %d\n", ret);
+		return;
+	}
+
+	led->enabled = 0;
+}
+
+static int regulator_led_brightness_set(struct led_classdev *led_cdev,
+					 enum led_brightness value)
+{
+	struct regulator_led *led = to_regulator_led(led_cdev);
+	int voltage;
+	int ret = 0;
+
+	mutex_lock(&led->mutex);
+
+	if (value == LED_OFF) {
+		regulator_led_disable(led);
+		goto out;
+	}
+
+	if (led->cdev.max_brightness > 1) {
+		voltage = led_regulator_get_voltage(led->vcc, value);
+		dev_dbg(led->cdev.dev, "brightness: %d voltage: %d\n",
+				value, voltage);
+
+		ret = regulator_set_voltage(led->vcc, voltage, voltage);
+		if (ret != 0)
+			dev_err(led->cdev.dev, "Failed to set voltage %d: %d\n",
+				voltage, ret);
+	}
+
+	regulator_led_enable(led);
+
+out:
+	mutex_unlock(&led->mutex);
+	return ret;
+}
+
+static int regulator_led_probe(struct platform_device *pdev)
+{
+	struct led_regulator_platform_data *pdata =
+			dev_get_platdata(&pdev->dev);
+	struct device *dev = &pdev->dev;
+	struct led_init_data init_data = {};
+	struct regulator_led *led;
+	struct regulator *vcc;
+	int ret = 0;
+
+	vcc = devm_regulator_get_exclusive(dev, "vled");
+	if (IS_ERR(vcc)) {
+		dev_err(dev, "Cannot get vcc\n");
+		return PTR_ERR(vcc);
+	}
+
+	led = devm_kzalloc(dev, sizeof(*led), GFP_KERNEL);
+	if (led == NULL)
+		return -ENOMEM;
+
+	init_data.fwnode = dev->fwnode;
+
+	led->cdev.max_brightness = led_regulator_get_max_brightness(vcc);
+	/* Legacy platform data label assignment */
+	if (pdata) {
+		if (pdata->brightness > led->cdev.max_brightness) {
+			dev_err(dev, "Invalid default brightness %d\n",
+				pdata->brightness);
+			return -EINVAL;
+		}
+		led->cdev.brightness = pdata->brightness;
+		init_data.default_label = pdata->name;
+	}
+
+	led->cdev.brightness_set_blocking = regulator_led_brightness_set;
+	led->cdev.flags |= LED_CORE_SUSPENDRESUME;
+	led->vcc = vcc;
+
+	/* to handle correctly an already enabled regulator */
+	if (regulator_is_enabled(led->vcc))
+		led->enabled = 1;
+
+	mutex_init(&led->mutex);
+
+	platform_set_drvdata(pdev, led);
+
+	ret = led_classdev_register_ext(dev, &led->cdev, &init_data);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static void regulator_led_remove(struct platform_device *pdev)
+{
+	struct regulator_led *led = platform_get_drvdata(pdev);
+
+	led_classdev_unregister(&led->cdev);
+	regulator_led_disable(led);
+}
+
+static const struct of_device_id regulator_led_of_match[] = {
+	{ .compatible = "regulator-led", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, regulator_led_of_match);
+
+static struct platform_driver regulator_led_driver = {
+	.driver = {
+		.name  = "leds-regulator",
+		.of_match_table = regulator_led_of_match,
+	},
+	.probe  = regulator_led_probe,
+	.remove = regulator_led_remove,
+};
+
+module_platform_driver(regulator_led_driver);
+
+MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
+MODULE_DESCRIPTION("Regulator driven LED driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:leds-regulator");